Various types of organic photoconductors are known. Most organic photoconductors are susceptible to attack by organic solvents of the type used in liquid toner electrophotography and are therefore unsuitable for such applications. These photoconductors include those which dissolve in the solvents and others which are caused to crack as the result of exposure thereto when they are under stress, especially when under tension.
It is known in the art to provide protective coatings for organic photoconductors. Examples of these coatings are given in U.S. Pat. Nos. 4,891,290 and 4,894,304.
U.S. Pat. No. 4,497,566 describes a system in which an organic photoconductor is heated to relieve tension in the photoconductor and then cooled immediately prior to its use in an imaging system. In the method described in this patent the photoconductor as a whole is in tension during the entire process with the tension being taken up by the backing layer after the heat treatment. This solution is impractical since it requires that the heat treatment be performed in situ as part of the imaging process itself.
U.S. Pat. No. 5,376,491, the disclosure of which is incorporated herein by reference, describes two methods of treatment for organic photoconductors which are susceptible to cracking used with liquid toner under mechanical stress. One of these methods involves the chemical treatment of the photoconductor to soften the photoconductive layer thereof and a second method which induces a compressive stress in the photoconductive layer. In use, the photoconductive layer, when the photoconductor is wrapped about a drum, remains in compressing and does not crack.
The other methodology for heat treatment of the photoconductor is to subject the photoconductor to tension, heat treat the photoconductor such that stress is relieved in the photoconductive layer, allowing the photoconductor to cool and then removing the stress, prior to utilizing the photoconductor in an imaging process.
R. C. U. YU, "Heat Shrinkage of Photoreceptor Belt onto a Drum" Xerox Disclosure Journal, Vol. 20, No. 2, Mar. 1, 1995-Apr. 30, 1995, describes a system whereby a photoreceptor is heat shrunk onto a drum, for later use.